Hyperkalemic periodic paralysis (HyperPP) is a muscle disorder characterized by episodic attacks of muscle weakness associated with an increase in serum potassium concentration. The disease is hyperkalemic periodic paralysis (MONDO_0008224). Also known as: Gamstorp disease, Gamstorp episodic adynamy, HYPP, adynamia episodica hereditaria, adynamia episodica hereditaria with or without myotonia, familial hyperPP, familial hyperkalemic periodic paralysis, familial hyperkalemic periodic paralysis (disorder) [ambiguous].